Single particle versus ensemble average: from power-law intermittency of a single quantum dot to quasistretched exponential fluorescence decay of an ensemble

Light-induced diffusion-controlled electron transfer is proposed as an underlying mechanism for the intermittency (power law and breakdown) of a single quantum dot and ensemble-averaged fluorescence decay. The intensity decay can be approximated to a stretched exponential expression. The physical links to the free energy gap, reorganization energy, electronic coupling, and diffusion correlation times are discussed. A procedure is described for extracting these molecular-based parameters from experiments and is demonstrated with examples using existing data.     

ZnO-TiO2的表面结构与表面性质

本文通过XRD相定量及低能离子散射谱研究了ZnO-TiO_2体系的结构. 实验表明, ZnO单层分散在TiO_2表面上, ZoO与TiO_2之间的结合较弱, 这种表面结合并不导致新的表面酸位。本文还讨论了ZnO-Al_2O_3、ZnO-SiO_2、ZnO-TiO_2三种含锌二元氧化物在结构、性能方面的明显差异及其根源。     

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine

Nanoscopic particles of oxovanadium phthalocyanine (VOPc, phase-II) with different particle sizes are prepared by aggregation of VOPc molecules in the presence of surfactants for the first time. A size effect in the region of nanoscale was observed in the UV-visible spectra. The photoconductivity of the nanoscopic VOPc is much higher than that of bulk VOPc. Copyright 1999 Academic Press.     

铈、镨二乙基磷酸盐的晶体结构

合成了Ce[PO_2(OC_2H_5)_2]_3和Pr[PO_2(OC_2H_5)_2]_3(简称Ce(DEP)_3和Pr(Pr(DEP)_3)。用四圆衍射仪测定了其晶体结构。它们均属三斜晶系,空间群P1。晶胞参数,对Ce(DEP)_3:α=10.324(4)A,b=12.861(4)A,c=13.998(5)A,x=106.49(3)°,β=112.83(4)° γ=115.61(3)°,V=1296(1)A~3,Z=2;对Pr(DEP)_3:α=10.27(1)A,b=11.81(1)A,c=12.51(1)A,x=109.93(9)°,β=111.9(9)°,γ=93.0(1)°,V=1293(3)A~3,Z=2。用Patterson法并经分块全矩阵最小二乘法修正,最后的R值,Ce的为0.1071,Pr的为0.1066。结构分析指出,两种配合物结构类似,Ce和Pr原子均由二乙基磷酸根的六个氧原子配位形成八面体构型。     

枸椽酸锗对小鼠免疫功能的影响

枸椽酸锗能明显提高小鼠血清溶血素抗体水平，增强二硝基氯苯（DNCB）致小鼠迟发型皮肤过敏反应。增加小鼠免疫器官胸腺和脾脏的重量，表明枸椽酸锗能增强小鼠体液免疫和细胞免疫水平。     

Studies of poly-<Emphasis Type="Italic">L</Emphasis>-lysine-starch nanoparticle preparation and its application as gene carrier

Anion starch nanoparticle (StNP) with a diameter of 50 nm was prepared in water-in-oil microemulsion, with soluble starch as raw materials and POCl₃ as crosslinking agent. PLL-StNP was prepared by linking poly-L-lysine (PLL) on the surface of StNP. At the same time, the size of PLL-StNP and its stability in aqueous solution were checked by AFM. The analysis of plasmid DNA binding, DNase I enzymatic degradation, toxicity and transfection were done. We discovered that PLL-StNP may be used as non-virus nanoparticle gene carrier. And we developed the method of preparing PLL-StNP gene carrier and used it in cell transfection. As non-virus gene carrier, PLL-StNP has some advantages, such as large load of DNA, high transfection efficiency, low cell toxicity and biodegradability.     

Electrospun nanofibers of poly（vinyl pyrrolidone）/Eu^3＋ and its photoluminescence properties

Nanofibers of poly（vinyl pyrrolidone） （PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and photoluminescence （PL）. The results indicated that, Eu^3＋ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu^3＋ hybrid nanofibers had favorable photoluminescence properties.     

双峰倍增配平法用于同步、导数-同步荧光法同时测定邻羟基苯甲酸和间羟基苯甲酸

邻羟基苯甲酸（ｏＨＢＡ）和间羟基苯甲酸（ｍＨＢＡ）荧光光谱严重重叠，同步及导数技术虽使选择性有所改善，但仍不能完全分辨开重叠谱。用双峰倍增配平计算法结合同步、一阶导数－同步荧光法对双组分体系（邻羟基苯甲酸／间羟基苯甲酸，ｐＨ１２介质）同时测定。结合计算的两种测定方法精密度、回收率和不同组分间浓度比范围均优于一阶导数－同步荧光法。     

智能型水凝胶

智能型水凝胶是一类具有广泛应用前景的功能高分子材料，但由于传统水凝胶存在一些缺点因而限制了其应用，因此近年来围绕提高传统水凝胶的性能做了大量研究工作。本文从四个主要方面综述了近年来智能型水凝胶改性的研究进展。     

流动注射微柱预分离富集荧光光度法测定肥料中的铈

用抗坏血酸将Ce(Ⅳ)还原为Ce(Ⅲ),以多聚磷酸钠作为增强剂,建立了铈的流动注射荧光分析法,考查了各种因素对测定Ce的影响.此方法线性范围为2.0×10-9～1.2×10-8 g·ml-1.采用流动注射微柱预分离富集测定了GBW07602标样和氨基酸微肥中的铈含量.测定结果与推荐值有良好的一致性.